rl_point is always zero

[okbob]

I try to use alternative API

/* For wcwidth() */
#define _XOPEN_SOURCE 700

#include <locale.h>
#include <ncurses.h>
#include <editline/readline.h>
#include <stdlib.h>
#include <string.h>
#include <wchar.h>

int kurzor;

static int		readline_proxy;
static bool		readline_proxy_is_valid = false;
char   *string = NULL;

/*
 * Zkopiruje znak z proxy do readline
 */
static int
readline_getc(FILE  *dummy)
{
	readline_proxy_is_valid = false;
	return readline_proxy;
}

/*
 * Touto funkci readline predava vysledek editace
 */
static void
readline_callback(char *line)
{
	free(string);
	string = NULL;

	if (line)
		string = strdup(line);


}

/*
 * Chceme mit zobrazeni ve vlastni rezii
 */
static void
readline_redisplay()
{
	/* do nothing here */
}

/*
 * Vrati (zobrazovaci) sirku retezce.
 */
static size_t
strnwidth(const char *s, size_t n)
{
	mbstate_t shift_state;
	wchar_t wc;
	size_t wc_len;
	size_t width = 0;
	size_t ch_width;

	memset(&shift_state, '\0', sizeof shift_state);

	for (size_t i = 0; i < n; i += wc_len)
	{
		wc_len = mbrtowc(&wc, s + i, MB_CUR_MAX, &shift_state);
		if (!wc_len)
			return width;

		if ((wc_len == (size_t) -1) || (wc_len == (size_t) -2))
			return width + strnlen(s + i, n - i);

		if (iswcntrl(wc))
			width += 2;
		else if ((ch_width = wcwidth(wc)) > 0)
			width += ch_width;
    }

    return width;
}

int
main()
{
	int		c = 0;
	bool	alt = false;
	char   *prompt = ": ";

	setlocale(LC_ALL, "");

	initscr();
	cbreak();
	noecho();

	/* ENTER neni \n */
	nonl();

	/*
	 * readline vyzaduje neprekodovany vstup tj
	 * vypnuty keypad a cteni vice bajtovych
	 * znaku po bajtech (emuluje se binarni
	 * cteni ze souboru v aktualnim kodovani)
	 */
	keypad(stdscr, FALSE);

	/*
	 * Instalace hooku - pokud se pouzije rl_getc_function,
	 * tak by se mel VZDY pouzit i rl_input_available_hook.
	 */
	rl_getc_function = readline_getc;
	rl_redisplay_function = readline_redisplay;

	/*
	 * Nechceme obsluhu signalu v readline, a nechceme tab
	 * complete (neni nakonfigurovano, hrozi pady.
	 */
	rl_catch_signals = 0;
	rl_catch_sigwinch = 0;
	rl_inhibit_completion = 0;

	/* Zahajeni editace */
	rl_callback_handler_install(prompt, readline_callback);

	/* Vlozi vychozi (default) text */
	rl_insert_text("Editaci ukonci 2x stisk ESCAPE");

	while (1)
	{
		int		cursor_pos;

		clear();

		mvaddstr(10, 10, rl_prompt);
		addstr(rl_line_buffer);

		if (string)
		{
			mvaddstr(12, 6, "text: ");
			attron(A_REVERSE);
			addstr(string);
			attroff(A_REVERSE);
		}

		/* nastav kurzor */
		cursor_pos = strnwidth(rl_prompt, SIZE_MAX) +
					 strnwidth(rl_line_buffer, rl_point);
		move(10, 10 + cursor_pos);

		refresh();

		get_wch(&c);

		/* ignoruj tabelatory */
		if (c == '\t')
			continue;

		if (c == 27)
		{
			if (alt)
				break;
			else
				alt = true;
		}
		else
			alt = false;

		readline_proxy = c;
		readline_proxy_is_valid = true;

		/* posli echo readline, ze jsou nova data k precteni */
		rl_callback_read_char();
	}

	rl_callback_handler_remove();

	endwin();
}

I am able to build this example, but the variables rl_point and rl_end are always zero. Unfortunately editline doesn't decode cursor keys or other control keys.

Is this functionality supported? I try to use editline from ncurses application.

tested on FC34

Name         : editline
Version      : 1.17.1
Release      : 3.fc34
Architecture : x86_64
Size         : 28 k
Source       : editline-1.17.1-3.fc34.src.rpm
Repository   : fedora
Summary      : A small compatible replacement for readline
URL          : https://troglobit.com/projects/editline/
License      : HSRL
Description  : This is a line editing library for UNIX. It can be linked into almost
             : any program to provide command line editing and history. It is call
             : compatible with the FSF readline library, but is a fraction of the
             : size (and offers fewer features).

[troglobit]

The integration of the GNU readline compat APIs, like the custom callbacks, is in a very raw and limited state. I tested them at one point three years when I first attempted to include them. It's however not something I've prioritized, and reception for it has been non-existent, so I'm not surprised your example doesn't work.

Editline is a very limited library, but cursor keys does work, provided it is built with --enable-arrow-keys, which is the configure default.

[okbob]

čt 5. 8. 2021 v 18:24 odesílatel Joachim Wiberg ***@***.***> napsal:

The integration of the GNU readline compat APIs, like the custom callbacks, is in a very raw and limited state. I tested them at one point three years when I first attempted to include them. It's however not something I've prioritized, and reception for it has been non-existent, so I'm not surprised your example doesn't work. Editline is a very limited library, but cursor keys does work, provided it is built with --enable-arrow-keys, which is the configure default.

ok When I run my example, then and when I press cursor keys, then I see ^[[D for left, and ^[[C for right key. So it looks like when I use callback functions, then cursor keys are not recognized. This behaviour is consistent if I use or don't use wide chars.

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[troglobit]

OK, maybe someone else is interested in helping out to fix this issue. Pull requests and patches are welcome! :)

[9999years]

I'm not sure about rl_point or rl_end, but I've added support for those arrow keys in #70.